Accumulator

ABSTRACT

An accumulator comprises a rigid container having a valve seat at its fluid inlet and a bladder therein carrying a valve element that engages the valve seat when the bladder is fully expanded. There is a dashpot connection between the valve element and a fixed spider in the inlet, to guide the valve element and so retard its motion when it is near the valve seat as to encourage radial rather than axial expansion and contraction of the bladder, thus preventing rubbing of the bladder on the container.

United States Patent References Cited UNITED STATES PATENTS 3/1889 Knight.....,........L...........

[72] Inventors Kazuo Sugimura;

Nobuyuki Sugimura, 1416 Sodeshi-cho, Shimizu-shi [21] AppLNo. 828,120

[22] Filed r e b e 2 ff. 1 mm w g m MM ewm amm J 40 n 46 99 r u ll e mi uwmm a mm Um 27 atm 44 .m w0 n n 22 P MA Shizuoka-ken, Japan May 27, 1969 [45] Patented May 25, 1971 [32] Priority June 1, 1968 [33] Japan [31] 43/37716 ABSTRACT: An accumulator comprises a rigid container having a valve seat at its fluid inlet and a bladder therein ca [54] ACCUMULATOR ing a valve element that engages the valve seat when the bladder is fully expanded. There is a dashpot connection 3 Claims, 4 Drawing Figs. [52] between the valve element and a fixed spider in the inlet, to guide the valve element and so retard its motion when it is near the valve seat as to encourage radial rather than axial expansion and contraction of the bladder, thus preventing rubbing of the bladder on the container.

0 8 3M 3 B 3 85 1 356 l n 6 4 M 1 3 m vms f t s.

Patented May 25, 1971 yzmuri k: 5 1mm 27 flazva in 017 ACCUMULATOR' This invention relates to an improved accumulator comprising a cylindrical liquid container and a gas bladder of approximately the same shape housed in said container.

The liquid container has at its lower end a port which communicates with an oil circuit comprising various kinds of pres sure liquid apparatus. When liquid is let in or out of the container through this port said gas bladder expands or contracts.

The object of the present invention is to provide an improved accumulator wherein there is a valve element on the gas bladder cooperable with a valve seat at the port to close the port when the bladder fully expands and liquid in the container is completely expelled from said port without any liquid left in the container.

Another object of the present invention is to provide such an accumulator wherein, when the gas bladder expands suddenly, the valve provided at the lower end of the gas bladder will not abruptly engage the valve seat provided around the port of the container so as not to injure these parts.

Still another object of the present invention is to slow the longitudinal movement of the bladder as the valve element on the bladder comes closer to the valve seat on the container.

A further object of the present invention is to provide means that overcomes the tendency of the bladder to float upwardly by buoyancy when liquid is present in the container, so that the bladder is not deformed into an irregular shape.

In order to achieve these objects, the accumulator of the present invention has the following features.

The accumulator comprises a cylindrical liquid container having a port at one end thereof provided with a valve seat and a gas bladder enclosed in said container having a valve at its lower end.

These two elements are connected by a liquid damper comprising a cylinder in which a piston is slidable with a loose fit, which piston bridges the port portion of said liquid container and the valve at the lower end of gas bladder.

The characteristics of the present invention will be more apparent from the following description with reference to the accompanying drawings.

FIG. 1 is a longitudinal section 'view of an accumulator of the present invention.

FIG. 2 is a longitudinal section view of an accumulator of a second embodiment of the present invention.

FIG. 3 is a fragmentary longitudinal section view of an accumulator of a third embodiment.

FIG. 4 is a fragmentary section view of an accumulator of a fourth embodiment. Now with reference to FIG. 1, there is shown an accumulator of the present invention comprising a liquid container 1 made of rigid material such as steel having substantial pressure resistance, in which is housed an elastic gas bladder 2 made of rubber or any other elastic material. Pressure liquid is introduced into the space between said container 1 and gas bladder 2. A gas valve 3 is provided on the top end of said gas bladder, projecting from the container 1, through which gas is forced into the bladder 2. A cap 4 is provided on this part to protect it against dust. The container 1 has at its bottom a liquid port 5 through which liquid is let into and out of the container 1.

Avalve seat 6 is formed at the inner periphery of said port 5. A rod 7 extends through the center of said valve seat 6 and the lower end of the rod 7 is secured to a boss 6" which is supported by a plurality of arms 6' extending to the valve seat 6.

Also the bladder 2 has at its lower end a valve 8 which serves to close or open said port 5 in moving into and out of engagement with said valve seat 6. Said valve 8 has a cylinder portion 9 projecting inwardly of the bladder. In this cylinder portion 9 a piston 10 is slidably engaged with a loose tit so that a clearance 11 is provided between the inner wall of the cylinder portion 9 and the piston 10. The piston 10 is rigidly attached to the top end of said rod 7 which extends with some clearance through an opening 8 provided in the center of said valve 8, the clearance between said rod 7 and valve 8 being designated by 12.

The upper cylinder chamber 9' above the piston 10 and the lower cylinder chamber 9" below the piston 10 are filled with liquid of the container through said clearances 11 and 12 respectively.

In FIG. 1 when liquid is forced into the container 1 through the port 5, the gas bladder 2 is compressed inwardly, reducing its capacity. But when liquid is discharged through the port 5 to the outer oil circuit (not shown), the gas in the bladder 2 expands whereby the valve 8 is moved towards the valve seat 6. In the latter instance, the volume of the cylinder chamber 9 is gradually decreased while the volume of the cylinder chamber 9" is enlarged. Since the rod 7 extends through the cylinder chamber 9", the variation ratio of the volume of cylinder chamber 9' is somewhat greater than that of the cylinder chamber 9". The liquid contained in the upper chamber 9 is forced through the clearance 11 into the lower chamber 9", but the surplus liquid therein will overflow through the clearance 12 into the container.

It can be seen that by properly selecting the respective clearances 11 and 12, it is possible to retard the speed of extension in a longitudinal direction of the bladder 2 to thus increase its relative speed of expansion in a radial direction.

Thus the gas bladder 2 will expand substantially more in a radial direction than in a longitudinal direction before the valve 8 contacts the valve seat 6, to insure that no liquid will be left sealed within the cylinder 1. Nor will there be a damage to any part caused by a hard hit of the valve 8 against the valve seat 6.

Since the rod 7 that is secured to the valve seat 6 is slidably engaged in the valve 8 that is provided at the lower end of the bladder, and since the piston 10 is securely attached to the upper end of the rod 7, the lower end of the gas bladder will never tend to float up if any buoyance is imparted to the bladder 2, as contrasted to the case of the free end of the conventional bladder.

Thus the bladder is kept in the position shown in the drawings and will never be susceptible to local damage by its irregular deformation. This is also true when the container 1 of the accumulator is set invertedly from the position shown in FIG. 1 or is set horizontally to suit convenience of installation.

Referring to FIG. 2, there is shown another type of container 21, the top end of which is wide open, and a bladder 22 is enclosed therein with its upper flanged portion 23 being inserted between the upper rim of the container 21 and a cover 24. A gas valve 25 extends through the cover by which gas is forced into the bladder 22 and is provided with a cap 26 against dust.

The container 21 has a port 36 through which liquid is introduced and which has a valve seat 30 on a part of its inner periphery. Inside this valve seat 30 there is provided a cylinder 27 which extends downwardly and is supported by arms 30' extending to the valve seat 30.

In said cylinder 27 a piston 28 is mounted with a loose fit so that there is provided clearance 29 between the wall of the cylinder 27 and the piston 28. In the top end of the cylinder 27 there is a hole 31 through which extends, with a clearance 34, a rod 33 hereinafter described, and there is a small opening 35 at the lower end of the cylinder 27. A valve 32 is provided at the lower end of the bladder 22 which moves toward and from engagement with said valve seat 30. A rod 33 projecting downwardly from the center of said valve 32 loosely fits in said guide hole 31, and the other end of the rod 33 is securely attached to said piston 28.

In this accumulator as the gas bladder 22 expands or contracts in a longitudinal direction, the piston 28 moves downwardly or upwardly whereby the liquid above and below the piston 28 flows through the clearances 29 and 34 and the opening 35, and fluid resistance thus retards the movement of the bladder 22 to some extent.

The accumulator shown in FIG. 3 is a somewhat different i from that shown in FIG. 1 in that the rod 7 has at its lower end a larger diameter portion 7'. In this accumulator when the gas bladder 2 expands from the position shown in solid lines to the position shown in chain lines the liquid in the upper cylinder chamber 9' flows through the clearance ll to the lower cylinder chamber 9" and further therefrom flows through the clearance 12 into the liquid container 1. I

As the gas bladder 2 moves to the position shown in chain lines, the clearance 12 is reduced so that the'flow resistance of the liquid is increased, thus slowing the expansion speed in a longitudinal direction of the bladder 2.

In this instance, assuming that the clearances 11 and 12 are made sufficiently large, they will not afford much hindrance to the expansion and contraction of the bladder 2 when the valve 8 is at some distance from its seat, but as the valve nears its seat during expansion of the bladder, they will offer substantial resistance to the expansion of the bladder. However they will not prevent the proper function of the accumulator.

The accumulator shown in FIG. 4 is similar to that shown in FIG. 2 except that the cylinder 27 has a smaller diameter portion 27 so that there is a variation in the clearance 29 between the piston 28 and the wall of the cylinder 27.

During the expansion of the gas bladder 22, the clearance 29 is relatively large until the piston moves from the position shown in solid lines to the position shown in chain lines. However after it has moved beyond the position shown with the chain lines, clearance 29 becomes relatively smaller so that the expansion speed in a longitudinal direction of the bladder is retarded.

The invention is not limited to the embodiments shown in the drawings. Any change or modification may be made without departing from the spirit of the invention.

We claim:

1. In an accumulator comprising a rigid container having a port at one end thereof through which liquid can flow in and out, a valve seat element on the container surrounding said port, a resilient gas filled bladder in the container, one end of which is secured to the container remotely from the port and which contracts and expands as liquid moves into and out of the container, and a valve element carried by said bladder at its other end for movement toward and from engagement with the valve seat element in consequence of expansion and contraction of the bladder, means for guiding the valve element in its motion toward and from the valve seat element and for retarding motion of the valve element when it is near the valve seat element so as to constrain-the bladder to expanding and contracting motion mainly in directions transverse to the axis of the port and thus minimizerubbing of the bladder against the interior of the container, said means comprising:

A..a rod having one of its ends rigidly secured to one of said elements and having its other end formed as a piston, said rod being substantially coaxial to the port; and

B. a cylinder rigidly secured to the other of said elements and in which said piston is received with clearance, said cylinder being closed at one end and having at its other end a wall which faces said one element and in which there is a hole through which the rod extends with clearance so that liquid rctardingly flows into and out of the cylinder through the clearance spaces around the rod and the piston.

2. The accumulator of claim 1, further characterized by:

said rod having an enlarged diameter portion near its first named end which enters said hole as the valve element nears the seat element to reduce the clearance between the rod and said wall and thus afford additional retardation of valve element motion when the valve element is near the seat element.

3. The accumulator of claim 1, further characterized by:

the bore of said cylinder having a reduced diameter portion at its end nearer said wall, cooperable with the piston when the valve element is near the seat element to afford additional retardation of valve element motion when the valve element is near the seat element. 

1. In an accumulator comprising a rigid container having a port at one end thereof through which liquid can flow in and out, a valve seat element on the container surrounding said port, a resilient gas filled bladder in the container, one end of which is secured to the container remotely from the port and which contracts and expands as liquid moves into and out of the container, and a valve element carried by said bladder at its other end for movement toward and from engagement with the valve seat element in consequence of expansion and contraction of the bladder, means for guiding the valve element in its motion toward and from the valve seat element and for retarding motion of the valve element when it is near the valve seat element so as to constrain the bladder to expanding and contracting motion mainly in directions transverse to the axis of the port and thus minimIze rubbing of the bladder against the interior of the container, said means comprising: A. a rod having one of its ends rigidly secured to one of said elements and having its other end formed as a piston, said rod being substantially coaxial to the port; and B. a cylinder rigidly secured to the other of said elements and in which said piston is received with clearance, said cylinder being closed at one end and having at its other end a wall which faces said one element and in which there is a hole through which the rod extends with clearance so that liquid retardingly flows into and out of the cylinder through the clearance spaces around the rod and the piston.
 2. The accumulator of claim 1, further characterized by: said rod having an enlarged diameter portion near its first named end which enters said hole as the valve element nears the seat element to reduce the clearance between the rod and said wall and thus afford additional retardation of valve element motion when the valve element is near the seat element.
 3. The accumulator of claim 1, further characterized by: the bore of said cylinder having a reduced diameter portion at its end nearer said wall, cooperable with the piston when the valve element is near the seat element to afford additional retardation of valve element motion when the valve element is near the seat element. 